While numerous peptide and aptamer biological drugs have promising properties as a drug candidate, it is known that the in vivo half-life of the biological drugs is short and ranges, for example, from several minutes to several hours since the biological drugs are easily degraded in the body by peptidase and nuclease, etc., or rapidly excreted through the kidneys (Sato A. K. et al., Curr Opin Biotechnol, 17, 638-642, 2006). To resolve the problem of instability and short sustain time of drug efficacy, a technique has been employed, wherein polyethylene glycol (PEG) is conjugated to the biological drugs (Veronese, F. M. & Pasut G., Drug Discov Today, 10, 1451-1458, 2005) to inhibit degradation by an in vivo enzyme and repress uptake by the kidneys and blood vessels, thereby extending retention time in blood of the drugs. However, such pegylation is problematic in that it takes a long time and requires specific optimizations depending on a binding material, and various molecular conjugates may also be produced due to the heterogeneous binding of the PEG molecules.
For the purpose of being used as a novel delivery platform, a hapten should meet the requirements of being nontoxic to animals and humans and not having physiological activity. Cotinine is a major metabolite of nicotine to which humankind has been exposed for a long time. Thus, cotinine is a hapten that is suitable as a novel delivery platform application. Also, cotinine is a relatively very stable material having LD50 of about 2-4 g/kg in a mouse (Riah O. et al., Toxicol. Lett., 109, 21-29, 1999), and no particular side effects have not been reported even in the 4-day administration at a daily dose of 1.8 g of cotinine (Bowman, E. R. & Mc, K. H., Jr., J. Pharmacol. Exp. Ther., 135, 306-311, 1962). Also, a metabolic process of cotinine in mammals has been clearly revealed, and the fact that the half-life of cotinine in serum is about 16 hours is also well known (Benowitz N. L. et al., 3rd Handb. Exp. Pharmacol., 29-60, 2009). In addition, cotinine does not exhibit physiological activity in humans, and any physiological and behavioral changes have not been reported even in the case of maximally uptaking 160 mg of cotinine for three days (Hatsukami, D. K. et al., Pharmacol. Biochem. Behav., 57, 643-650, 1997).
Meanwhile, aptamers have been used for various analyses and experiments, since they can be specifically folded in a three dimensional form, thereby being capable of binding to a target with high-affinity and specificity, similarly to an antibody. The conventional methods for preparing a complex with an antibody using an aptamer are mainly achieved by conjugating the aptamer to biotin or digoxigenin and then allowing the resulting conjugate to form a complex with avidin or an anti-digoxigenin antibody.
The present inventors have prepared a complex in which an anti-cotinine antibody is bound to a conjugate of a binding material and cotinine by using cotinine as a hapten, and have accomplished the present invention by finding out that the complex may retain the specific reactivity and the biological function of the binding material, and the capabilities of inducing complement-mediated cell cytotoxicity (CDC), antibody-dependent cell cytotoxicity (ADCC), and a prolonged in vivo half-life, which are intrinsic characteristics of an antibody.